1. Field of the Invention
The present invention relates to a differential, and more specifically to a differential having means for restricting a differential motion.
2. Description of the Prior Art
It is preferable for a four wheel drive car to be provided with a differential between the front axle and the rear axle so as to prevent a braking phenomenon in rounding a turn. When a differential is provided between the front axle and the rear axle, the provision of means for restricting a differential motion is necessary in order to prevent the loss of driving force due to the wheels slipping. Combinations of viscous-couplings have been used as the means for restricting a differential motion. But the viscous-couplings generate fairly large restrictive torque on the differential motion when a differential rotation is fairly small so that it causes the braking phenomenon in rounding a turn with a small radius. As shown in Japanese Patent Laid-Open Publication No. 61-155028, locking mechanisms for the differential such as hydraulic clutches, etc., also have been proposed. But the locking mechanisms for the differentials such as hydraulic clutches, etc., have complicated constructions and need spaces wherein they can be placed. As a result the size of the differential becomes large. Moreover, the provision of mechanisms for controlling the hydraulic clutches, etc., is necessary.